By the numbers: The virtualisation options for private cloud hopefuls

VMware, Hyper-V… XenServer? The choice is yours

The playas

From the earliest days of simple virtualisation, the dramatic development and availability of features in the enterprise hypervisor turned them from a basic P2V tool for reducing hardware into a powerful arsenal of abilities and tools that a physical server platform couldn’t even begin to dream of.

Here’s a run-through of some of the best and most important features, by platform, starting with the forerunner – VMware vSphere – and their XenServer/Hyper-V equivalents:

vCenter: The centralised management solution for a VMware virtual data centre. This is the beating heart of your virtual environment and without vCenter, none of the amazing features would be possible. Has recently transitioned from a Windows VM with a SQL/SQL Express database requirement to a dedicated appliance with built-in custom database.

• XenServer equivalent – Citrix XenCenter
• Hyper-V equivalent – Hyper-V Manager, System Center Virtual Machine Manager

vMotion: Live VM migration between hosts without downtime. Requires shared storage and networking between hosts, plus a low-latency link, but in recent iterations can be carried out long-distance.

• XenServer equivalent – XenMotion
• Hyper-V equivalent – Hyper-V Live Migration

Storage vMotion: Similar to vMotion, but used to migrate running virtual machines between different data stores for live storage migration.

• XenServer equivalent – Storage XenMotion
• Hyper-V equivalent – Hyper-V Storage Live Migration

High Availability: Utilising heartbeat connectivity checks between hosts (and additional, individual VM monitoring if required) to ensure virtual machines stay up during any eventuality. If a host is lost through hardware, network or power failure, virtual machines will be automatically brought up on other hosts with spare capacity.

• XenServer equivalent – High Availability
• Hyper-V equivalent – High Availability

Fault Tolerance: During a regular High Availability failover, virtual machine uptime will be lost for the time taken for the host loss to be detected, plus the time taken for virtual machines to restart. Fault Tolerance maintains a second, standby copy of a virtual machine on a second host running milliseconds behind the original, ready to go immediately in the event of primary host loss.

• XenServer equivalent – None
• Hyper-V equivalent – None

Distributed Resource Scheduling: An automated workload management solution that distributes virtual machines between hosts according to resource requirements, to ensure the most efficient use of the virtualised platform. Can be fully automated or notify administrators of virtual machine moves that will better distribute the workload.

• XenServer equivalent – XenServer Workload Balancing
• Hyper-V equivalent – None

Distributed Power Management: An additional automated workload management solution that makes use of integrated lights-out management (HP iLO, Dell iDRAC, IBM IMM) on host servers to power hardware off at times of low-load to save on power usage, then switch them back on when the workload demands.

• XenServer equivalent – None
• Hyper-V equivalent – None

Hardware Hot-Add: Allows for the on-the-fly addition of vCPU, RAM, hard disks or other peripherals to be powered on and running virtual machines without disruption. Requires a supported guest operating system; hot-add is supported in Windows Server Enterprise versions, but not Standard.

• XenServer equivalent – None (removed in 5.6)
• Hyper-V equivalent – RAM and SCSI disks only

vSphere Replication: Allows replication of virtual machine clusters between multiple data centre environments, without relying on an underpinning storage array replication. Can be used in conjunction with Site Recovery Manager for a full disaster recovery solution.

• XenServer equivalent – XenServer Site Recovery
• Hyper-V equivalent – Hyper-V Replica

vShield: A relatively new security suite within VMware that – when combined with a compatible storage vendor – allows you to offload anti-virus and other security software functions to a dedicated control appliance, reducing installed software and performance overheads on protected VMs.

• XenServer equivalent – None
• Hyper-V equivalent – None